Memory and Hard Drives, Clearing Up the Confusion

by : Derick Nigro



Today I would like to share with you a question sent in from a reader who asks; "What is the difference between a hard drive and memory?" That is an excellent question, and one that gets confused quite often. To answer your question it will be a good idea to start with the basics. A hard drive is a mechanical case about the size of a paperback book, used to store information within your computer. The main components of a hard drive consist of platters or disks, which are stacked together and spin at high speeds. A spindle, which rotates the platters. And finally, an actuator arm, that travels across the disk to read or write data.

Memory or RAM (Random Access Memory) as it is commonly known, is a series of microchips, which is inserted into sockets on a motherboard. Since RAM can be removed from the motherboard, it can easily be replaced or upgraded. RAM like the hard drive, also stores information, hence the confusion. Now that we have a understanding of what the devices do, lets move on to the differences. A hard drive is used for long-term storage and is what we call non-volatile storage. What this means is when you shut down your computer the information saved to your hard drive is retained.

Everything in your computer from your operating system to the songs you listen to is saved within your hard drive. Your computer uses RAM as temporary storage, also referred to as volatile storage, data within RAM is removed once power is lost. RAM and hard drives differ greatly in actual storage capacity. Your average hard drive is approximately 80-300GB. While in contrast, a typical computer will have about 512MB - 2 GB of memory installed. Since RAM is temporary storage, it does not require the large storage capacity that your hard drive needs. Your computer can access data from RAM much faster than it could from a hard drive. The reason for this is unlike a hard drive, where the actuator arm must scan across platters to access information, RAM has no moving parts, and data is obtained almost instantly.

Let me give you an example of how memory and your hard drive work together. When you launch an application like a word processor, the computer accesses the hard drive, reads the data required to open the program, and loads that data into RAM. Every word you type is stored in RAM. I am sure you are aware of what happens when you get halfway through typing your word document and you suddenly lose power, all your hard work is lost. However, if the document had been saved before the power failure occurred, then the document would have been written to the hard drive. When power is restored, you simply start your computer, launch the word processor, open your saved document , and continue where you left off.

To summarize, hard drives constantly load data into RAM. Data that is loaded into RAM stays there until it is no longer needed, or you restart your system. Both devices store data, Memory is temporary, a hard drive is permanent. I hope this article was able to give you a better understanding of your computers two main storage devices, and the differences between them.